A brief analysis of the working principle of high-speed sound barriers

From the analysis of the concepts of noise and noise, we can know that the difference between them is not only the difference of pleasant and unpleasant in objective feeling, but also the difference of frequency analysis can be carried out in physical measurement. According to the characteristics of its frequency composition and intensity distribution, the scene-type sound barrier can be distinguished from the chaotic sound by frequency analysis and the horizontal axis represents the frequency.

The vertical axis represents the intensity of each frequency component (sound pressure level or sound intensity level). The figure drawn in this way is called a spectrum diagram. The spectrum diagram of noise is composed of discontinuous discrete spectrum lines and the spectrum lines of each frequency component on the spectrum diagram of noise are arranged very densely, with continuous spectrum characteristics.

In such a spectrum, the sound energy of the high-speed sound barrier is continuously distributed in the entire audio range. Most of the sound barriers of air conditioner units have continuous noise frequencies, also known as atonal noise. Some machines such as blowers, induction motors, etc. have continuous noise frequencies in the spectrum of sound. It also has a very obvious discrete frequency component. This component is generally determined by the speed of rotating parts such as motor rotors or reducer gears. The high-speed sound barrier makes the noise have a distinct tone, but in general it still has the nature of noise, which is called modulated noise.